PID Temperature Controller

Temperature-Programmed XPS

Before starting

  1. Mount sample on a PBN sample holder. E-beam sample holders distort XPS spectra upon flowing electric current.
  2. Make sure that that current flowing through the PBN heater is not affecting thermocouple readings.  Make a short test with current ca. 0.8A set for a short period of time. While increasing current to ca. 0.8 A and decreasing it to 0A, watch the temperature reading. If up-down variation in the temperature reading is following increase-decrease in the preset current, thermocouple readings must be fixed. Check the grounding. Sample should be grounded, as well as one pole of the heater. Sometimes to remove and place whole sample carrier back on the manipulator can improve contacts on thermocouple wires.
  3. If possible, try limited temperature ramp on a sample which cannot be damaged by impropriate heating, such as crystal substrate during cleaning cycle. If the temperature ramp is not linear, check limit values set for power supply. Check also if correct PID parameters are loaded to PID controller memory. If necessary, retune PID parameters.

SES sequence set up

An example of sequence used for Temperature programmed XPS can be found in PBACH7 PC:
D:\Users\BACH\FIRB\Dec2014 DBP on Ag(110)\SeqTimeResolvedPES.seq

Regions C1s_Fixed (fixed mode, 10s) and Br3d_Fixed (fixed mode, 8s) were selected during TP-XPS. Period for the acquisition was about 21s.

Other regions serve for calibrations. C1s_swept and Br3d_swept regions were created by copying *_fixed regions and selecting swept mode instead of fixed mode. Both swept and fixed regions are typically measured before a TP-XPS measurement. Their ratio serves as intensity calibration curve for the fixed mode, as each energy channel in fixed mode has different sensitivity. The FE_swept region should be set for kinetic energy of the Fermi edge and serves for binding energy scale calibration.

Acquiring TP-XPS

  1. Make sure that Io and T (temperature) external signals are selected to be recorded together with photoemission regions. SES -> Set-up -> Signals -> tick Io, T. In the sequence, select region -> Edit and make sure that signals are selected.
  2. Select regions to be measured during the temperature ramp (Typically those in fixed mode). 
  3. Sweep sequence in “Add dimension” and “Repeat until stopped” mode.
  4. Start “Temperature to SES” program on PBACH5 PC; enable analog output (under Settings tab; it should be enabled by default); if desired, enable temperature program in Temperature program tab; hit Start button to start temperature recording and temperature program, if selected.
  5. If temperature monitor only is selected, one can check temperature reading in SES software, for example in Calibration-> Voltages-> View -> Signals
  6. Run SES acquisition
  7.  Start manually temperature ramp/program (unless Temperature program in Temperature to SES software is selected).
  8. When the temperature ramp/program is finished, stop the acquisition from Sequence-> Stop after sequence.

Data postprocessing

  1. Normalize to Io
  2. Normalize intensities in fixed mode according the intensity in swept mode
  3. Calibrate binding energy scale
  4. (Linearize and interpolate data along the time/temperature scale)

Last Updated on Tuesday, 11 May 2021 21:37